1. Field
Example embodiments relate generally to methods of driving a display panel, and more particularly to methods of driving a liquid crystal display panel and apparatuses for driving the liquid crystal display panel.
2. Description of the Related Art
A liquid crystal display (“LCD”) apparatus is a kind of flat display apparatuses, which is now used broadly. The LCD apparatus applies voltages to molecules of a liquid crystal to adjust arrangements of the molecules thereby changing optical characteristics of liquid crystal cells, such as birefringence, optical activity, dichroism and light scattering to display an image.
In the LCD apparatus, a liquid crystal is disposed between an array substrate on which a pixel electrode is formed and a color filter substrate on which a common electrode is formed. Transmittance of a pixel is adjusted by alignment of the liquid crystal, which is changed by an electric field between the pixel electrode and the common electrode such that an image is displayed on the LCD apparatus.
Recently, in order to solve low side visibility problem of a conventional LCD apparatus, LCD apparatuses, having a patterned vertical alignment (“PVA”) mode, an in-plane switching (“IPS”) mode, etc., are developed. However, a LCD apparatus having a PVA mode has afterimage defects and a limited side viewing angle, and a LCD apparatus having an IPS mode has a disadvantage that luminance of a displayed image is low. In order to solve these disadvantages, a LCD apparatus having a plane to line switching (“PLS”) mode is developed.
The LCD apparatus having the PLS mode includes a liquid crystal. The liquid crystal may be a positive-type (positive kind) liquid crystal or a negative-type (negative kind) crystal. Because a splay angle of the positive-type liquid crystal is greater than a splay angle of the negative-type liquid crystal, transmittances of a central portion of the pixel electrode having a slit pattern and a central portion of the slit pattern are low in the LCD apparatus including the positive-type liquid crystal. Alternatively, because the splay angle of the negative-type liquid crystal is less than the splay angle of the positive-type liquid crystal, transmittance of the LCD apparatus including the negative-type liquid crystal is greater than transmittance of the LCD apparatus including the positive-type liquid crystal.
The LCD apparatus including the negative-type liquid crystal and having the PLS mode includes an alignment layer, and an alignment direction of the alignment layer is substantially perpendicular to a direction of a pixel electrode pattern. Ionic impurities in the negative-type liquid crystal are more than ionic impurities in the positive-type liquid crystal. In the LCD apparatus including the negative-type liquid crystal, the ionic impurities may be attached to the alignment layer by a thermal fluctuation of the liquid crystal, and a luminance difference and an afterimage between images may occur.
If a pattern is displayed for a long time in the LCD apparatus, the pattern may remain on the display panel when another image is displayed on the display panel. The remaining pattern is called to an afterimage. A major reason causing the afterimage is a residual DC voltage generally generated by discordance between an electric center of a data voltage and a common voltage.
In an LCD apparatus having a plane to switching (“PLS”) mode, the voltage-time curve (V-T curve) in a positive polarity and V-T curve in a negative polarity do not coincide with each other so that the discordance between the electric center of a data voltage and a common voltage may naturally occur. Thus, the afterimage problem may be serious in the LCD apparatus having the PLS mode compared to the LCD apparatuses having the twisted nematic (TN) mode and the vertically aligned (VA) mode.